Pipe bending method and apparatus



June 7, 1938.

L. CARI.` l 2,119,875 PIPE BENDING METHOD AND APPARATUS Filed Jan. 14, v19s? INVENTOR LOUIS Cdr! Patented June 7, 1938 UNITED STATES PATENT oFElcE `HP11; BENDING METHOD AND APPARATUS Louis Carl, Brooklyn, N. Y. Application January 14, 193i?, Serial No. 120,554

15 Claims.

This invention relates to the art of bending pipe and is directed more particularly to a method and apparatus whereby pipe may be satisfactorily bent without undesirable distortion. The invention is especially directed, insofar as the apparatus is concerned, to an articulated mandrel adapted to occupy the interior of the pipe during the bending thereof and to be simultaneously operated upon by apparatus hereinafter more fully described to partake of longitudinal and rotary motion which preclude the freezing of the mandrel in the pipe and will iron out and render uniform the bore of the pipe when the bending operation is completed.

The mandrel of the present invention embodies a succession of non-yieldable units arranged end to end and successively interconnected in a manner to permit their relative articulation in all directions, but to positively lock them together against appreciable relative rotation. The mandrel unitsof the present invention are individually of very simple construction and yet of great strength. They interengage with one another, after the manner of the links of a chain, so that, while the engagement is sufciently tight to lock them against unlimited rotation, there is suiiicient give, so that there is in effect a substantially universal pivotal connection between successive sections without the use of com- 3o plicated connections. This arrangement permits of rotation of the entire assembly by rotation of one terminal section or unit thereof.

The method of this invention comprises the` simultaneous bending of a pipe with mandrel therein and concurrent rotation and longitudinal movement of the mandrel during the entire bending operation on the pipe.

Features of the invention, other than those adverted to, will be apparent from the hereinafter detailed description and claims, when read in conjunction with the accompanying drawing.

The accompanying drawing illustrates apparatus for carrying out the method of this invention and specific mandrel construction, but the showing of the drawing is to be understood as illustrative, only, and not as dening the limits of the invention. i

Figure 1 is a plan view, more or less diagrammatic in character, illustrating the manner of 50 carrying out the method of this invention with the mandrel shown in Figures 2 and 3.

Figure 2 shows a portion of the length of the mandrel of this invention.

Figure 3 is an end View of one of the mandrel units with one link thereof in section.

The mandrel of this invention is made up of a succession of units or sections I,'which, `aside from the terminal section 2, are of the same construction. Each section I is of substantially barrel shape with at ends 3 provided therein with recesses 4 which impart to the unit I-beam cross section of great strength, well adapted to withstand any radial pressures to which the mandrel may be subjected.

' Between the recesses 4 is the web 5 and this web is provided with pockets 6, so positioned that said pockets will extend from the base of the recesses 4 partially into the flanges 1, as shown best in Figure 2. The pockets 6 are adapted to receive the ends of U-shaped keepers or links 8 which are adapted to fit snugly into said pockets and are welded in place' therein. The links are welded 'in place as the successive units are assembled with links of the successive units interlocked with respect to one another, as shown in Figure 2, and when'thus welded in place, these units are permanently connected to one another in a strong and rugged manner. The recesses 4 are made with quite a taper, so that the holes or seats 6 extend well into the Wall of this taper and, when 25 welded in place, the links will thus be reinforced for substantially half their length by the ilanges I of the units, so that the twisting action which results from rotation of the mandrel during articulationgof the parts, as hereinafter described, will not disrupt the structure.

The terminal section 2 serves the function of a sizing unit. It is of slightly larger diameter than the units I and is of a size to give a finished internal diameter to the bent pipe through which it is drawn. It may conveniently be made of barrel shape like the units I, vbutvwithout the recesses in the ends. Straight-through holes 9 extend through the unit 2 and are adapted to receive a shackle Ill which is engaged with the link 8 of the next adjacent unit I and locked in place thereto by nuts II at the opposite face of the unit 2. I

1n utilizing the mandrel described to carry out the method of this invention, I may satisfactorily proceed as shown in Figure l. Here the pipe, in the process of being bent, is indicated at P; A mandrel of the character shown in Figure 2 is shown in the pipe and the pipe is operated upon by any appropriate conventional pipe bending mechanism mounted on the base or table I2. Bending dies and other pipe bending machinery are well known and, inasmuch as the present invention is adapted to be carried out with any appropriate form of mechanism for this purpose, I have not considered it necessary to specifically disclose any particular mechanism.

According to the method of this invention, as hereinbefore stated, the mandrel is rotated and simultaneously withdrawn as the bending operation on the pipe proceeds. Consequently suitable mechanism is provided to accomplish this result and while this mechanism may vary, a Very satisfactory form is shown in Figure 1. Here the foremost unit I of the mandrel is connected by a rigid link I5 to a threaded arbor I6 which passes through a threaded boss I1 of a yoke I8. This yoke is rigidly spaced from a plate I3, rigid with the base I2, by means of spacing rods I9 to which the yoke is pinned or otherwise rigidly locked in position. The rods I9 extend beyond the yoke I8 to form guide rods or slides for a power operated prime mover 2l, shown in the form of an Vand withdrawal of the mandrel.

electric motor, having guides 22 embracing the rods 20 and free to slide thereon. The motor spindle is adapted to have driving connection with the outboard end of the threaded arbor I6 and, in practice, suitable speed reducing gears are preferably incorporated inl this connection and may be built into the motor casing, so that, as the motor operates, the arbor I6 will be rotated.

Inasmuch as the connections between the threaded arbor I6 and the mandrel within the pipe are such as to preclude relative rotation between them, it necessarily follows that the rotation of the arbor will cause rotation of the mandrel. Furthermore, inasmuch as the yoke I8 cannot move, it necessarily follows that the rotating arbor I6 must longitudinally travel through the threaded boss I'l and bring about longitudinal movement of the mandrel in the pipe for the forward end of the pipe is seated against an abutment or stop I3 and the pipe is thus held in place against the pull of the mandrel therein.

The threaded arbor I6 is caused to rotate during the entire bending operation on the pipe and this will result in the simultaneous rotationof the mandrel and its longitudinal movement through the pipe in such manner as to preclude undesirable crimping of the pipe. This operation may be lubricated, if desired, by soap, water or otherwise, but is not ordinarily essential. 'I'he movement of the mandrel may be relatively slow or may be at high speed depending on conditions and on the speed at which the bending operation is taking place. In any event, the mandrel should be entirely withdrawn from the pipe before the bending dies, with which the pipe is associated, are released, so that, when the dies are opened, the pipe `will come therefrom with a uniform internal diameter and without undesirable crimping at any point.

'Ihe mandrel made according to the invention, as hereinbefore described, is particularly adapted for use in carrying out the method of this invention because the lmandrel units are so constructed and are of such strong and rugged character, that they are well able to withstand tremendous strains that may take place when pipes of large sizes are bent with concurrent rotation that the individual units have no moving parts for the links of each unit are welded to form a homogeneous joint or inherent part of the units. Furthermore the units may be said to be onepiece units, interftting progressively with one another throughout the length of the mandrel in a manner to properly articulate as may be It is notable necessary to accommodate themselves to the bend in the pipe.

'I'he marked simplicity of this invention commends itself to modern pipe bending problems. There is no complicated mechanism to get out of order. The individual elements are rugged and may be manufactured economically and assembled economically. sembly is such that if a flaw occurred in the welding, the structure is nevertheless sufliciently reinforced, by virtue of the interfitting relation described, to hold together even though a weld of the character under consideration might vwell break if it were alone depended upon to hold the structure together.

The foregoing detailed description sets forth the invention in its preferred practical forms, but the invention is to be understood as commensurate with the appended claims.

Having thus fully described the invention, what I claim as new and desire to secure by Letters Patent is:

1. A pipe bending mandrel comprising a succession of barrel shaped units positioned end to end and recessed at their opposite ends to form the units into I-beam cross section, there being provided in the opposite faces of said section spaced apart link seats formed conjointly in the Web and anges of said section, and two U- shaped links interfitted with one another between each two adjacent units and with their free ends welded into the link seats of the respective units.

2. A pipe bending mandrel comprising a succession of barrel shaped units positioned end to end and recessed at their opposite ends to form the units into I-beam cross section, there being provided in the opposite faces of said section spaced apart link seats formed conjointly in the web and flanges of said section, and two U- shaped links intertted with one another between each two adjacent units and with their free ends welded into the link seats of the respective units, and a sizing unit forming lone terminal unit of the mandrel and of a diameter slightly greater than the diameter of the other units of the mandrel.

3. In an apparatus of the character described, a mandrel comprising articulated sections, means for simultaneously imparting rotation to said mandrel and concurrently longitudinally moving;

the same, and an abutment past which said mandrel is Withdrawable from a pipe resting against said abutment.

4. In an assembly of the character described, a mandrel having articulated sections locked against rotation with respect yto one another and adapted to be positioned within a pipe, a threaded arbor secured against rotation to the-mandrel, a threaded member mounted rigidly in position and through which the arbor is adapted to neously rotating and withdrawing the mandrel' Furthermore the as-y tiguous ends of eachtwo adjacent units collectively constitute a chamber, and a universal joint positioned within each chamber and connected to both contiguous units, said universal joint securing adjacent 'units against relative rotation, but permitting articulation between said units in all lateral directions.

9. A pipe bending mandrel comprising a succession of substantially barrel-shaped'units positioned end to end in closely spaced relation with the opposite ends of each unit recessed, whereby the recesses of each two contiguous units collec-- tively constitute a chamber, a pair of interlocking rigid links positioned in each chamber with the respective links of each pair rigidly secured 'to the respective adjacent units.

10. A pipe bending mandrel comprising a succession offsubstantially barrel-shaped units p0- sitioned end to end in closely spaced relation with the opposite ends of each unit recessed, whereby the-recesses of each two contiguous units collectively constitute a chamber, a pair of interlocking rigid U-shaped links positioned in each chamber with the free ends of the respective links of each pair rigidly secured to the respective adjacent units.

11. A pipe bending mandrel comprising a succession of substantially barrel-shaped units positioned end to end in closely spaced relation to -one another with both of the opposite ends of each unit recessed, whereby the recesses at contiguous ends of each two adjacent units collectively constitute a chamber, and a universal joint positioned within each chamber and connected to both contiguous units, said universal joint securing adjacent units against relative rotation, but

permitting articulation between said units in all lateral directions, and a rigid non-yielding sizing unit secured to one terminal unit of said units of the mandrel and of a diameter slightly greater than the diameter of the other units of the mandrel.

12. A pipe bending mandrel comprising a succession of substantially barrel-shaped units. positioned end to end in closely spaced relation to one another with both of the opposite ends of each unit recessed, whereby the recesses at contiguous ends of each two adjacent units collectively constitute a chamber, and a universal joint positioned within each chamber and connected to both contiguous units, said universal joint securing adjacent units against relative rotation, but permitting articulation between said units in all lateral directions, and a rigid non-yielding sizing unit secured to one terminal unit of -said units of the mandrel and of a diameter slightly greater than the diameter of the other units oithe mandrel, said sizing unit being locked against rotation, but for universal cross axial articulation to the adjacent terminal unit of the mandrel.

13. A pipe bending mandrel comprising a succession of substantially barrel-shaped units positioned end to end in closely spaced relation to one another with both of the opposite ends of each unit`recessed, whereby the recesses at contguous ends of each two adjacent units collectively constitute a chamber, a universal joint po' sitioned within each chamber and connected to both contiguous units, said universal joint securing adjacent units against relative rotation, but

. permitting articulation between said units in all lateral directions, and a rigid non-yielding substantially barrel-shaped sizing unit secured to one terminal unit of said units of the mandrel and of a diameter -slightly greater than the diameter of the other units of the mandrel.

14. In an apparatus of the character described, a mandrel comprising articulated.y sections and adapted to be positioned within a pipe to permit the longitudinal bending thereof by externally applied force Without crushing the pipe, means for simultaneously imparting rotation to said mandrel and concurrently longitudinally moving the same within the'pipe. andmeans for holding the pipe stationary against longitudinal movement while the mandrel is so moved and while the pipe is bent by the application of force applied externally thereto.

15. In an assembly of the character described, a mandrel having articulated sections locked against rotation with respect to one another and adapted to be positioned within a pipe, a threaded arbor secured against rotation' to the mandrel, a threaded member mounted rigidly in position and through which the arbor is adapted to turn, means for rotating said arbor to rotate the mandrel and simultaneously move the same longitudinally through the pipe in which it is positioned, and means for withholding the pipe against longitudinal movement while the mandrel is being withdrawn from said pipe.

LOUIS CARL. 

